What is the correct ratio of breathing gas during a dive?

The correct ratio of breathing gas pressure during a dive is based on the principle that for every 10 meters (33 feet) of seawater descent, the pressure increases by approximately 1 atmosphere. This means that at the surface, the pressure is 1 atmosphere due to the weight of the air above us, and as a diver descends, the pressure increases due to the weight of the water.

For instance, at a depth of 10 meters, a diver experiences a total pressure of 2 atmospheres (1 atmosphere from the air above the water and 1 atmosphere from the water itself). This relationship is crucial for divers to understand as it directly affects the way they manage their breathing gas supply and their overall buoyancy.

Understanding this ratio helps divers avoid issues related to pressure changes, such as barotrauma or nitrogen narcosis, and is essential for planning gas consumption and determining the appropriate amount of breathing gas needed for any given dive depth.